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2001 Pontiac Grand Prix 3.8 motor occasional smoke

Tiny
GREATGUY1650
  • MEMBER
  • 2001 PONTIAC GRAND PRIX
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 194,000 MILES
I just got a 2001 Grand Prix GT, 3.8 liter with194.000 miles. I know the car and its previous owner. It runs fine but now has a problem on deceleration of making a dense blue smoke cloud for a second or two and then stopping. It doesn't do this at highway speed or constant travel in town. It also seems to like to smoke after left hand turns just for a brief time. It starts, idles and sounds good otherwise. Any suggestions as to the cause?
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Thursday, August 18th, 2011 AT 8:08 PM

9 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,747 POSTS
It sounds like either a bad valve seal or a partially plugged drain port in the cylinder head. Remove the valve covers and check for excessivebuild up of dirt in the drain ports and check the valve seals to see if they are cracked or damaged.
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Thursday, August 18th, 2011 AT 8:14 PM
Tiny
GREATGUY1650
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  • 6 POSTS
I will try those ideas on Saturday. Would these causes come about suddenly and to the tune of a quart of oil in 40 miles? It just started Tuesday and only for brief very cloudy periods. Could a PVC org EGR system do it? It seems like oil is being forced in when the vacuum increases. Thank you for the help !
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Thursday, August 18th, 2011 AT 8:25 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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That is interesting. What happens if you open the oil fill cap with the engine running?
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Thursday, August 18th, 2011 AT 8:34 PM
Tiny
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I haven't tried it but I will now.I will write back in 5 minutes.
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Thursday, August 18th, 2011 AT 8:38 PM
Tiny
GREATGUY1650
  • MEMBER
  • 6 POSTS
It started up with a little amount of smoke for 5 seconds and then purred to an idle. When I opened the cap it almost stalled but recovered to run not as smooth as before. Once the cap went back on it purred again. What does the vacuum fluctuation mean?
Thanks for the test, by the way!
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Thursday, August 18th, 2011 AT 8:47 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,747 POSTS
Check the PCV valve to make sure it isn't plugged first. Let me know what you find.
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Thursday, August 18th, 2011 AT 8:49 PM
Tiny
GREATGUY1650
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  • 6 POSTS
My PCV valve looks like it has been used as an oil pump. It is soaked in oil and barely rattles. Does that look like the likely and only suspect?
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Thursday, August 18th, 2011 AT 9:10 PM
Tiny
GREATGUY1650
  • MEMBER
  • 6 POSTS
Update:
I replaced the PCV valve and reduced the smoking to just a little and infrequent during 10 minute test run. But on waiting a minute to make a left turn near home I started a thick white/blue cloud that was huge. It lasted only a few seconds but went from house to house across the street.
I came home and discovered the MAP sensor had come apart in two pieces and was just sitting in place.I just replaced it but I saw smoke starting up on my down the street trip so I came home.
When I take off the oil cap now it shuts the engine down.
Do all these symptoms point to something specific?
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Friday, August 19th, 2011 AT 8:46 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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My main concern is that there is too much blow-by from the rings caused by engine wear. If there is a lot of pressure coming from the oil fill hole when running, that tells me compression is getting past the rings into the crank case. You may want to check engine compression to confirm that it is within spec. The other thing for just the small amount of blue smoke sounds like valve seals or a partially plugged cylinder head drain.
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Saturday, August 20th, 2011 AT 12:01 AM

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